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    Re: A good clock for a few billion years
    From: David C
    Date: 2019 May 5, 20:53 -0700

    have demonstrated that the clock can produce a second with precision in the parts per quintillion—that’s 10¹⁹,

    Here is a grizzle. It is something that has annoyed me for a very long time. Why are words like trillion used in the popular press instead of the appropriate SI prefix?  In addition, I would expect a physicist working on a super accurate clock to use SI prefixes rather than ambiguous terms.

    I know that the British and American billions are different. When I looked up metric prefixes in Wikipedia (yes, I know, but please do not comment) I became even more confused. A quadrillion is either 10 power 24  or 10 power 18. Fortunately a quintillion has onl;y one meaning.

    When I set my wristwatch It is important I know how many exaseconds it is since the big bang!

    P.S. How can the physicist prove that his clock is as accurate as he claims. If his clock has gained 1 second since the Big Bang that must be relative to something. What?

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